Join NASA for Webcast About STS-131 Mission and NASA Langley Research Center/National Alliance of Black School Educators Lecture Series

Join the Digital Learning Network on Jan. 27, 2010, from 4:00 p.m. - 5:00 p.m. EST, for a webcast about the upcoming STS-131 mission, which is scheduled for launch no earlier than March 18, 2010. Dorothy Metcalf-Lindenburger, educator and mission specialist, is a member of the STS-131 crew and will be involved in several robotics tasks during the mission. Join the DLN for this webcast to learn more about the mission and activities to support robotics in the classroom.

NASA Langley Research Center/National Alliance of Black School Educators Lecture Series for 2010

Join NASA's Langley Research Center and the National Alliance of Black School Educators for a series of free, interactive programs that allow you and your students to learn more about our home planet and the universe beyond through webcasts.

Go on a tour of the planets and explore the surface features, atmospheric structure and composition, and moon and ring systems of each planet. Learn about the terrestrial or inner planets (Mercury, Venus, Earth and Mars) and the features they have in common, such as solid surfaces surrounded by atmospheres composed mostly of carbon dioxide (Venus and Mars) or nitrogen and oxygen (Earth). Investigate the outer planets (Jupiter, Saturn, Uranus and Neptune) and the features they share such as thick and massive atmospheres with no evidence of a solid surface beneath.

The Earth System
Feb. 26, 2010, 1 p.m. - 2:00 p.m. EDT

The components of the Earth system, the lithosphere (the solid planet), the hydrosphere (the water), the atmosphere (the air) and the biosphere (life), will be discussed. Learn about the various processes on the Earth system including the structure of the Earth's interior and surface, the formation of impact craters, volcanism and volcanic craters, the circulation of the atmosphere and oceans, the water cycle (evaporation, condensation and precipitation), the formation of clouds, and meteorological phenomena. The interactions between the components of the Earth system will be also discussed.

Mars is a cold, dry, very inhospitable planet. Its thin atmosphere has a surface pressure of only about 6 millibars (the pressure of Earth's atmosphere is about 1013 millibars). Scientists now think that early Mars was a very hospitable planet with abundant surface water in the form of lakes, rivers and even planetary-scale oceans. They believe it had an atmospheric pressure comparable to that of Earth. What caused the very divergent evolutionary paths of Earth and Mars? Scientists believe that some 500 million years after its formation about 4.6 billion years ago, Mars lost its planetary dipole magnetic field. The field had protected its atmosphere from the "sand-blasting" effects of the solar wind, the continuous stream of energetic protons, electrons and ions emitted by the sun into interplanetary space. Once Mars lost its planetary magnetic field, the direct interaction of the energetic solar wind particles with the atmosphere resulted in the planet's losing more than 99 percent of its atmosphere. Once Mars lost the bulk of its atmosphere, surface liquid water was no longer stable and was either lost to space and/or migrated to the subsurface of Mars as frozen water.

The temperature of the surface of Earth and the other planets is controlled by incoming solar radiation and the outgoing thermal or infrared radiation generated at the surface by the absorption of the incoming solar radiation. As the surface-emitted thermal radiation travels upward through the atmosphere, certain atmospheric gases absorb and then re-emit the radiation. This process results in an additional warming of the surface. This additional warming is called the "greenhouse effect." Gases that absorb and then re-emit thermal radiation are called "greenhouse gases." Carbon dioxide, while only a very minor gas in the atmosphere, is an important greenhouse gas. Measurements indicate that atmospheric concentrations of carbon dioxide are increasing, most likely as a result of certain human activities, such as the combustion of fossil fuels for transportation and energy generation and the burning of vegetation for deforestation and other land-clearing activities. The causes and consequences of global warming will be discussed.

For more information about this series of webcast events, visit http://dln.nasa.gov/dln/.

If you have any questions about this lecture, please contact Dr. Arlene S. Levine at 757-864-3318 or Arlene.S.Levine@nasa.gov.